This invention relates generally to an automotive transmission or the like. More particularly, it relates to a multiple speed ratio transmission with apparatus for retarding gear rotation when a non-synchronized gear is to be engaged.
In recent years there have been many improvements in automotive drive trains, including improvements relating to devices for shifting manual transmissions. Generally, for transmissions incorporating a plurality of forward speed ratios and a reverse speed ratio, the shift control apparatus provides appropriate crossover positions for the shift stick. Each crossover position selects a shift fork or the like, which may be moved to engage a speed ratio. In a four speed and reverse transmission, for example, one crossover position might select the first and second forward speed ratios, another the third and fourth forward speed ratios, and yet another the reverse speed ratio.
Copending U.S. application Ser. No. 153,128 filed May 27, 1980 discloses shift control apparatus wherein a shift stick is movable laterally to rotate a shift rail about its longitudinal axis for crossover selection. In each crossover position the shift stick is movable longitudinally to slide the shift rail along its axis so as to engage the selected speed ratio. In the first and second positions, the shift rail is slidable to engage respectively the first or second forward speed ratio and the third or fourth forward speed ratio. In the third position, the shift rail is slidable to engage the reverse speed ratio.
When the reverse idler gear slides in the gear-engaging direction, it comes into meshing engagement with other gears in the reverse gear train. As these other gears may be rotating as part of a constant mesh transmission, it is desirable to brake them before this meshing engagement takes place in order to avoid the clashing of gears.
Copending U.S. application Ser. No. 92,886 filed Nov. 9, 1979 discloses shift control apparatus including a modified synchronizer which functions as a countershaft brake. This is a complicated, expensive brake mechanism which takes effect after crossover selecion; that is, during the reverse gear-engaging movement of the reverse idler gear. In some instances this may not be soon enough to avoid gear clash.
Thus, there remains a need in the art for a simple, inexpensive brake mechanism which will be effective to eliminate gear clash in a transmission of the type disclosed.